diff --git a/aosp/dynamic_partition_control_android.cc b/aosp/dynamic_partition_control_android.cc
index 19ea6ec..a309b6e 100644
--- a/aosp/dynamic_partition_control_android.cc
+++ b/aosp/dynamic_partition_control_android.cc
@@ -1424,11 +1424,11 @@
   return metadata_device_ != nullptr;
 }
 
-std::unique_ptr<android::snapshot::ISnapshotWriter>
+std::unique_ptr<android::snapshot::ICowWriter>
 DynamicPartitionControlAndroid::OpenCowWriter(
     const std::string& partition_name,
     const std::optional<std::string>& source_path,
-    bool) {
+    std::optional<uint64_t> label) {
   auto suffix = SlotSuffixForSlotNumber(target_slot_);
 
   auto super_device = GetSuperDevice();
@@ -1443,29 +1443,26 @@
       .timeout_ms = kMapSnapshotTimeout};
   // TODO(zhangkelvin) Open an APPEND mode CowWriter once there's an API to do
   // it.
-  return snapshot_->OpenSnapshotWriter(params, std::move(source_path));
+  return snapshot_->OpenSnapshotWriter(params, label);
 }  // namespace chromeos_update_engine
 
 std::unique_ptr<FileDescriptor> DynamicPartitionControlAndroid::OpenCowFd(
     const std::string& unsuffixed_partition_name,
     const std::optional<std::string>& source_path,
     bool is_append) {
-  auto cow_writer =
-      OpenCowWriter(unsuffixed_partition_name, source_path, is_append);
+  auto cow_writer = OpenCowWriter(
+      unsuffixed_partition_name, source_path, {kEndOfInstallLabel});
   if (cow_writer == nullptr) {
+    LOG(ERROR) << "OpenCowWriter failed";
     return nullptr;
   }
-  if (!cow_writer->InitializeAppend(kEndOfInstallLabel)) {
-    LOG(ERROR) << "Failed to InitializeAppend(" << kEndOfInstallLabel << ")";
+  auto fd = cow_writer->OpenFileDescriptor(source_path);
+  if (fd == nullptr) {
+    LOG(ERROR) << "ICowReader::OpenFileDescriptor failed";
     return nullptr;
   }
-  auto reader = cow_writer->OpenReader();
-  if (reader == nullptr) {
-    LOG(ERROR) << "ICowWriter::OpenReader() failed.";
-    return nullptr;
-  }
-  return std::make_unique<CowWriterFileDescriptor>(std::move(cow_writer),
-                                                   std::move(reader));
+  return std::make_unique<CowWriterFileDescriptor>(
+      std::move(cow_writer), std::move(fd), source_path);
 }
 
 std::optional<base::FilePath> DynamicPartitionControlAndroid::GetSuperDevice() {
diff --git a/aosp/dynamic_partition_control_android.h b/aosp/dynamic_partition_control_android.h
index 9851a99..830901b 100644
--- a/aosp/dynamic_partition_control_android.h
+++ b/aosp/dynamic_partition_control_android.h
@@ -17,16 +17,16 @@
 #ifndef UPDATE_ENGINE_AOSP_DYNAMIC_PARTITION_CONTROL_ANDROID_H_
 #define UPDATE_ENGINE_AOSP_DYNAMIC_PARTITION_CONTROL_ANDROID_H_
 
+#include <array>
 #include <memory>
 #include <set>
 #include <string>
 #include <string_view>
-#include <array>
+#include <vector>
 
 #include <base/files/file_util.h>
 #include <libsnapshot/auto_device.h>
 #include <libsnapshot/snapshot.h>
-#include <libsnapshot/snapshot_writer.h>
 
 #include "update_engine/common/dynamic_partition_control_interface.h"
 
@@ -102,14 +102,14 @@
 
   // Partition name is expected to be unsuffixed. e.g. system, vendor
   // Return an interface to write to a snapshoted partition.
-  std::unique_ptr<android::snapshot::ISnapshotWriter> OpenCowWriter(
+  std::unique_ptr<android::snapshot::ICowWriter> OpenCowWriter(
       const std::string& unsuffixed_partition_name,
       const std::optional<std::string>& source_path,
-      bool is_append) override;
+      std::optional<uint64_t> label) override;
   std::unique_ptr<FileDescriptor> OpenCowFd(
       const std::string& unsuffixed_partition_name,
       const std::optional<std::string>&,
-      bool is_append = false) override;
+      bool is_append) override;
 
   bool MapAllPartitions() override;
   bool UnmapAllPartitions() override;
diff --git a/aosp/mock_dynamic_partition_control_android.h b/aosp/mock_dynamic_partition_control_android.h
index e940e50..cc6ebf3 100644
--- a/aosp/mock_dynamic_partition_control_android.h
+++ b/aosp/mock_dynamic_partition_control_android.h
@@ -17,13 +17,13 @@
 #include <stdint.h>
 
 #include <memory>
+#include <optional>
 #include <set>
 #include <string>
 
 #include <gmock/gmock.h>
 
 #include <libsnapshot/cow_writer.h>
-#include <libsnapshot/snapshot_writer.h>
 
 #include "payload_consumer/file_descriptor.h"
 #include "update_engine/aosp/dynamic_partition_control_android.h"
@@ -96,11 +96,11 @@
               PrepareDynamicPartitionsForUpdate,
               (uint32_t, uint32_t, const DeltaArchiveManifest&, bool),
               (override));
-  MOCK_METHOD(std::unique_ptr<android::snapshot::ISnapshotWriter>,
+  MOCK_METHOD(std::unique_ptr<android::snapshot::ICowWriter>,
               OpenCowWriter,
               (const std::string& unsuffixed_partition_name,
                const std::optional<std::string>& source_path,
-               bool is_append),
+               std::optional<uint64_t> label),
               (override));
   MOCK_METHOD(std::unique_ptr<FileDescriptor>,
               OpenCowFd,